Relationship between growth rate and undercooling in Pt-added Y1Ba2Cu3O7−x

1996 ◽  
Vol 11 (5) ◽  
pp. 1114-1119 ◽  
Author(s):  
A. Endo ◽  
H. S. Chauhan ◽  
Y. Nakamura ◽  
Y. Shiohara
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Parabolic Equation ◽  
Growth Rates ◽  
Crystal Size ◽  
Experimental Conditions ◽  
Seed Crystals ◽  
Cooling Method ◽  
Increasing Trend ◽  
Good Agreement

Y1Ba2Cu307−x (Y123) crystals were grown by two different methods, the constant undercooling solidification and the continual cooling method, with top seeding by Sm123 seed crystals in order to investigate a relationship between undercooling (ΔT) and a growth rate (R). The crystals of Y123 with a sharp faceted interface, which consisted of {100} and {001} faces, grew epitaxially from the seed. It was found that the growth rates of {100} face (Ra) and that of {001} face (Rc) showed an increasing trend with increasing ΔT, and Rc was faster than Ra within these experimental conditions, ΔT < 20 K. The relation between R and ΔT follows the parabolic equation, viz. Ra ∝ ΔT1.9 and Rc ∝ ΔT1.3 for {100} and {001} faces, respectively. The simulated crystal size using the R and ΔT relations obtained from the constant undercooling method showed good agreement with experimental data by the continual cooling.

Diffusion model for deposition of epitaxial GaAs layers prepared by the MOCVD method

1991 ◽  
Vol 56 (10) ◽  
pp. 2020-2029
Author(s):  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma ◽  
Rudolf Hladina
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Kinetic Model ◽  
Gas Phase ◽  
Substrate Surface ◽  
Deposition Process ◽  
Hydrogen Atmosphere ◽  
Epitaxial Gaas ◽  
Kinetics Of ◽  
Good Agreement

The authors proposed and treated quantitatively a kinetic model for deposition of epitaxial GaAs layers prepared by reaction of trimethylgallium with arsine in hydrogen atmosphere. The transport of gallium to the surface of the substrate is considered as the controlling process. The influence of the rate of chemical reactions in the gas phase and on the substrate surface on the kinetics of the deposition process is neglected. The calculated dependence of the growth rate of the layers on the conditions of the deposition is in a good agreement with experimental data in the temperature range from 600 to 800°C.

Measurement of growth rates for single crystals and pressed tablets of CuSO4.5 H2O on a rotating disc

1989 ◽  
Vol 54 (11) ◽  
pp. 2951-2961 ◽  
Author(s):  
Miloslav Karel ◽  
Jaroslav Nývlt
Keyword(s):  
Growth Rate ◽  
Single Crystal ◽  
Single Crystals ◽  
Growth Rates ◽  
Diffusion Coefficients ◽  
Preferred Orientation ◽  
Rotating Disc ◽  
Dissolution Rates ◽  
Rates Of Growth ◽  
Good Agreement

Measured growth and dissolution rates of single crystals and tablets were used to calculate the overall linear rates of growth and dissolution of CuSO4.5 H2O crystals. The growth rate for the tablet is by 20% higher than that calculated for the single crystal. It has been concluded that this difference is due to a preferred orientation of crystal faces on the tablet surface. Calculated diffusion coefficients and thicknesses of the diffusion and hydrodynamic layers in the vicinity of the growing or dissolving crystal are in good agreement with published values.

scholarly journals Crystal growth rates in polar firn

1993 ◽  
Vol 18 ◽  
pp. 208-210
Author(s):  
Hitoshi Shoji ◽  
Atau Mitani ◽  
Kohji Horita ◽  
Chester C. Langway
Keyword(s):  
Growth Rate ◽  
Plastic Deformation ◽  
Crystal Growth ◽  
Growth Rates ◽  
Strain Field ◽  
Crystal Size ◽  
Ice Core ◽  
Transformation Process ◽  
Ice Crystals ◽  
Air Bubbles

Continuous crystal-size measurements made on the G6 Antarctic ice core (100m deep) show enhanced growth rates above a depth of 30 m (Zone 1) and in the interval between 70 and 80 m (Zone 2). Crystal growth in Zone 1 most probably takes place by a process of sublimation and condensation. The higher growth rate in Zone 2 is most probably related to the pore close-off transformation process in which a non-uniform strain field is created to form air bubbles by plastic deformation and “cannibalization” of individual ice crystals.

The evolution and bifurcation of a pendant drop

1994 ◽  
Vol 278 ◽  
pp. 83-100 ◽  
Author(s):  
R. M. S. M. Schulkes
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Satisfactory Agreement ◽  
Growth Rates ◽  
Pendant Drop ◽  
Large Growth ◽  
Comparison With Experimental Data

In this paper we calculate how a pendant drop evolves at the end of a nozzle when the volume of the drop increases steadily with time. We find that the character of the evolution is strongly dependent on the growth rate of the drop and the radius of the nozzle. Typically we find that once the drop has become unstable, two bifurcations occur shortly after each other when the growth rate of the drop is slow. For large growth rates the bifurcations are well-separated in time. We are able to calculate the volumes of the drops after the bifurcations. A comparison with experimental data shows a satisfactory agreement.

scholarly journals Crystal growth rates in polar firn

1993 ◽  
Vol 18 ◽  
pp. 208-210 ◽  
Author(s):  
Hitoshi Shoji ◽  
Atau Mitani ◽  
Kohji Horita ◽  
Chester C. Langway
Keyword(s):  
Growth Rate ◽  
Plastic Deformation ◽  
Crystal Growth ◽  
Growth Rates ◽  
Strain Field ◽  
Crystal Size ◽  
Ice Core ◽  
Transformation Process ◽  
Ice Crystals ◽  
Air Bubbles

Continuous crystal-size measurements made on the G6 Antarctic ice core (100m deep) show enhanced growth rates above a depth of 30 m (Zone 1) and in the interval between 70 and 80 m (Zone 2). Crystal growth in Zone 1 most probably takes place by a process of sublimation and condensation. The higher growth rate in Zone 2 is most probably related to the pore close-off transformation process in which a non-uniform strain field is created to form air bubbles by plastic deformation and “cannibalization” of individual ice crystals.

Review and synthesis of experimental data on organic matter decomposition with respect to the effect of temperature, moisture, and acidity

1998 ◽  
Vol 6 (1) ◽  
pp. 25-40 ◽  
Author(s):  
Charlotta Walse ◽  
Björn Berg ◽  
Harald Sverdrup
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Organic Matter ◽  
Soil Moisture ◽  
Mass Loss ◽  
Growth Rates ◽  
Fungal Growth ◽  
Effect Of Temperature ◽  
Decomposition Model ◽  
Bacteria And Fungi

A review and synthesis of experimental decomposition data was performed with the objective of finding parameter values for a decomposition model. Experimental data were retrieved from the literature and included data on mass loss rates, nitrogen mineralization rates, carbon dioxide evolution rates, and growth rates of bacteria and fungi. Environmental variables included in the synthesis were air temperature, soil moisture, and soil acidity (concentration of H+ and Al3+ in soil solution). The variables were assumed to act as separate, multiplicative rate regulating factors on soil microbial processes. The model outline includes four organic matter pools: (i) easily decomposable compounds, (ii) holocellulose, (iii) lignin, and (iv) resistant compounds. It was assumed that the decomposition of the easily decomposable substances can be modeled as the growth rate of bacteria, while the decomposition of lignin and resistant compounds can be modeled as the growth rate of fungi. The decomposition of the substances included in the holocellulose pool was assumed to follow an intermediate function. Results show that enough data are available for the parameterization of a model of the suggested type. The effect of temperature on decomposition rate seems to increase with decreasing nutrient concentration of the substrate. Decomposition rates increase with relative soil moisture saturation. Bacterial growth rates are generally more sensitive to low pH than fungal growth rates. Decomposition of mixed organic material is inhibited in an intermediate fashion. The combined impact of H+ and Al3+ on the growth rates of bacteria and fungi can be modeled with an ion-exchange expression, preferably the Vanselow expression. It was concluded that some additional experiments would be needed for further model development purposes. Such experiments should be set up as mass loss experiments and last for a minimum of 2 weeks.Key words: decomposition, model, acidification, aluminum, pH.

The Mechanism for Ultrananocrystalline Diamond Growth: Experimental and Theoretical Studies

2006 ◽  
Vol 956 ◽  
Author(s):  
Paul William May ◽  
Yuri A. Mankelevich
Keyword(s):  
Growth Rate ◽  
Crystal Size ◽  
Calculated Data ◽  
Chemical Vapor ◽  
Diamond Growth ◽  
Experimental Conditions ◽  
3 Dimensional ◽  
Ultrananocrystalline Diamond ◽  
Hot Filament ◽  
Experimental And Theoretical Studies

ABSTRACTAr/CH4/H2 gas mixtures have been used to deposit microcrystalline diamond, nanocrystalline diamond and ultrananocrystalline diamond films using hot filament chemical vapor deposition. A 3-dimensional computer model was used to calculate the gas phase composition for the experimental conditions at all positions within the reactor. Using the experimental and calculated data, we show that the observed film morphology, growth rate, and across-sample uniformity can be rationalized using a model based on competition between H atoms, CH3 radicals and other C1 radical species reacting with dangling bonds on the surface. Proposed formulae for growth rate and average crystal size are tested on both our own and published experimental data for Ar/CH4/H2 and conventional 1%CH4/H2 mixtures, respectively.

Use of spectral analysis to estimate short-term periodicities in growth rates of brook trout Salvelinus frontinalis

1997 ◽  
Vol 54 (7) ◽  
pp. 1532-1541 ◽  
Author(s):  
W Aboul Hosn ◽  
P Dutilleul ◽  
D Boisclair
Keyword(s):  
Growth Rate ◽  
Spectral Analysis ◽  
Growth Rates ◽  
Repeated Measures ◽  
Brook Trout ◽  
Short Term ◽  
Experimental Conditions ◽  
Relative Growth Rates ◽  
Repeated Measures Design ◽  
Periodic Components

We used spectral analysis to investigate the periodic components of relative growth rates (on a mass and length basis) in two groups of six\b young-of-the-year brook trout (Salvelinus fontinalis). Fish were measured every 2 days for 25 days according to a repeated measures design in time. The predominant frequency components were estimated at the end of a stepwise procedure involving the analysis of the multifrequential periodogram. We found mainly two superimposed periodic components that resulted in short rhythms; these had a period of about 5 and 10 days for the growth rate in mass and of about 4 and 6 days for the growth rate in length (R2 = 91% for mass and 90% for length, both including an autocorrelation term). Repeatability of rhythms was assessed by ANOVA of the finite Fourier transform, which showed that the two groups of fish reared under the same experimental conditions exhibited growth rhythms that were not significantly different from each other. On that basis, we present a harmonic model which predicts short-term variation in growth rate of brook trout in mass (R2pred = 0.73, with an autocorrelation term) and in length (R2pred = 0.72).

Calculation of 15N NMR Parameters of Azides and Some Related Compounds. Revisiting the Methylation of Nitrous Oxide N2O

2011 ◽  
Vol 66 (10) ◽  
pp. 1079-1082 ◽  
Author(s):  
Bernd Wrackmeyer
Keyword(s):  
Experimental Data ◽  
Nitrous Oxide ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr ◽  
Experimental Conditions ◽  
Nmr Parameters ◽  
Related Compounds ◽  
Good Agreement

The results of a calculation of 15N NMR parameters (chemical shifts and coupling constants) of azides and related compounds are in reasonably good agreement with experimental data, even for triazadienyl fluoride, F-N3. The reaction between [CH3]+ and nitrous oxide, N2O, can yield either an O- or an N-methylated cation, [Me(N2O)]+. The calculated 15N NMR parameters clearly indicate that under the experimental conditions N-methylation to give [MeNNO]+ is preferred instead of the methoxydiazonium ion [MeONN]+ previously proposed.

Physiological consequences of nighttime temperature for a tropical, herbivorous lizard (Cyclura nubila)

1986 ◽  
Vol 64 (4) ◽  
pp. 836-840 ◽  
Author(s):  
Keith A. Christian
Keyword(s):  
Growth Rate ◽  
Food Consumption ◽  
Constant Temperature ◽  
Growth Rates ◽  
Passage Time ◽  
Digestive Efficiency ◽  
Experimental Conditions ◽  
Temperature Group ◽  
Ad Libitum ◽  
Nighttime Temperatures

Hatchling Cuban iguanas (Cyclura nubila) were reared for 38 weeks under three experimental conditions: nighttime temperatures of 15, 25, and 35 °C. All groups experienced a temperature of 35 °C during the day, and all were given food and water ad libitum. Growth rate (in terms of mass and length) increased with increasing nighttime temperature. The iguanas held at constant 35 °C were also more robust (defined as mass/length); this difference was not explained by the amount of fat. Passage time of food through the gut was shorter for the constant temperature group, which also consumed more food per day. There was no difference in digestive efficiency among groups, and the differences in growth rates were a result of the differences in food consumption. Constant temperature was apparently not detrimental for this tropical, herbivorous lizard. More data are required before useful generalizations concerning voluntary hypothermia in reptiles can be made.

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